Introduction to Biology BIOS 1010 7A

Copyright © 2011 Pearson Education Inc. Biology: Life on Earth, 9e

Introduction to BiologyBIOS 1010 7A

Sarah Jeffers


Chapter 1

Introduction to Life on Earth


Levels of Organization of Matter

Fig. 1-1

& Species


What Are The Characteristics of Living Things?

Living things are composed of cells– Living things are both

complex and organized

Fig. 1-8


The Cell Is the Smallest Unit of Life

Fig. 1-2


• All organisms consist of one or more cells• The cell is the simplest structural and functional unit of life.

The Cell Is the Smallest Unit of Life

• Cells are the building blocks of all• plants and animals.

• All new cells come from the division• of pre-existing cells.

• Cells are the smallest units that perform• all vital physiological functions.

• Cell

• Division

• Growth• New• cells

• Nutrients• Wastes

• O2

• CO2

• The cell theory

• A characteristic of all living things is organization.• Thus the name of all living things as organisms.


The Domains and Kingdoms of Life

Fig. 1-11

The “Tree of Life”


How Do Scientists Categorize the Diversity of Life?

Categorizing life– There are exceptions to any simple set of rules used to

distinguish the domains and kingdoms, but three characteristics are particularly useful– Cell type– The number of cells in each organism– Energy acquisition


How Do Scientists Categorize the Diversity of Life? Classification into a domain or kingdom is based on

3 characteristics:1. Cell type

• Bacteria• Archaea

• Eukarya



3 characteristics:2. Number of cells

• Bacteria• Archaea

• Eukarya



3 characteristics:3. Energy Acquisition

Autotroph vs. HeterotrophSelf-feeding Other-feedingPhotosynthesis Digest external

food

Plants, some Archaeasome Bacteriasome Protists

Fungi,ArchaeaBacteriaAnimalssome Protists


How Are Organisms Named And Classified? Taxonomy – naming and classifying organisms

– Scientific name: two part Latin name

– Genus (closely related species)– species (populations that can interbreed)


How Are Organisms Named And Classified? Taxonomy – naming and classifying organisms

– Scientific name: two part Latin name

– Examples: Sialia (Bluebirds)

Sialia sialis Sialia mexicana Sialia currucoides(eastern) (western) (mountain)


How Are Organisms Named And Classified? Phylogeny – evolutionary history

– Similarities from a common ancestor– Not similarities from convergent evolution– Phylogenic trees



1. List the three precepts of the cell theory.2. Can you describe the levels of biological

organization?3. Can you name and briefly describe the three

domains of life?4. Can you explain how scientists discovered that

prokaryotes fall into two domains?5. Can you explain how scientists name and categorize

diverse forms of life?6. Can you explain why phylogenetic classifications

sometimes change?

Review Questions


Historical approaches to studying life– The belief that some events happen through supernatural

forces (e.g., the actions of Greek gods)– The belief that all events can be traced to natural causes

that we can comprehend (natural causality)– Corollary: Evidence gathered from nature has not

been deliberately distorted to fool us

• What is Science?


What is Science?

Scientific principles underlie all scientific inquiry– Natural causality is the principle that all events can be

traced to natural causes– Natural laws apply to every time and place– Scientific inquiry is based on the assumption that people

perceive natural events in similar ways


The scientific method is the basis for scientific inquiry– Observation– Question– Hypothesis– Prediction– Experiment or Observation– Conclusion

What is Science?


The scientific method 1.Observation of a specific phenomenon2.The observation, in turn, leads to a question3. The question leads to formulation of a

hypothesis, based on previous observations, that is offered as an answer to the question

4.The hypothesis leads to a prediction, typically expressed in “if…then…” language

5.The prediction is tested by carefully controlled manipulations called experiments

6.The experiments produce results that either support or refute the hypothesis, allowing the development of a conclusion

What is Science?


The scientific method– Scientific experimentation tests the assertion that a single

variable causes a particular observation

– Controls are incorporated into experiments– Controls keep untested variables constant

What is Science?


The Scientific Method

Fig. 1-4


The Experiments of Francesco Redi

Fig. E1-1


The Experiments of Malte Andersson

Fig. E1-2


Limitations of the scientific method– One can never be sure all untested variables are

controlled– Conclusions based on the experimental data must

remain tentative



Communication is crucial to science– Results of experimentation must be communicated

thoroughly and accurately to other scientists for repetition– Repetition by other scientists add verification that findings

can be used as the basis for further studies



Science can be accidental– In the 1920s, bacteriologist Alexander Fleming grew

bacteria in cultures – One of the bacterial cultures became contaminated with

a mold(Penicillium) – Fleming nearly destroyed the culture when he noticed the

mold Fleming hypothesized that the mold produced an antibacterial substance



Scientific Theory

What does Scientific theory mean?– A scientific theory differs in definition from that of

everyday usage– Many people use the word theory to mean hypothesis,

or an “educated guess”


– A scientific theory is a general explanation for important natural phenomena– It is extensively and reproducibly tested– If compelling evidence arises, a theory may be

modified– Described as a natural law

– New scientific evidence may prompt radical revision of existing theory– For example, the discovery of prions

Scientific Theory


The discovery of prions– Before 1980, all known infectious diseases contained

DNA or RNA– In 1982, Stanley Prusiner showed that the infectious

sheep disease scrapie is caused by a protein (a “protein infectious particle,” or prion)

– Prions have since been shown to cause “mad cow disease” and diseases in humans

– The willingness of scientists to revise accepted belief in light of new data was critical to understanding and expanding the study of prions

Scientific Theory

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Introduction to Biology BIOS 1010 7A